ApertureGotchi

Okay. (Please delete this post if it doesn't work for you) On the tamagotchi color, if you tamagotchi has been an adult for one sunrise already, you can "cheat" to make it think that it is ready to mate. First, at any time of day, set the clock to one minute before your character goes to sleep. For example, if it goes to sleep at 8:00, then set it to 7:59. When your character falls asleep after one minute, set the clock to 11:59 pm. Wait one minute until it it 12:00 am. Lastly, set the clock to 6:59 am, and wait one minute for your tamagotchi to wake up. When it has woken up, the matchmaker option should not be grayed out anymore. PLEASE NOTE: This ONLY works if you tamagotchi has been at least one sunrise an adult. It will not work if you do it twice and your adult is not one sunrise oldI have tried this twice for different characters and it has worked both times in the past.

ApertureGotchi

I am not sure, but I think it won't. You see, on the +Color, how long you have to wait to mate is determined by sunrises and going to bed, etc... So the iD L works with a certain number of hours of being an adult. So I do not think it will work. Because you cannot increase or decrease hour count. I have not received my iD L yet, so I have yet to test it.
And, by the way, the TMGC+C "cheat" may take several tries until the option is activated. Make sure you follow the instructions exactly.